Tuesday, 2 July 2013

Android checkbox example

// siddhu vydyabhushana // 8 comments
In Android, you can use “android.widget.CheckBox” class to render a checkbox.
In this tutorial, we show you how to create 3 checkboxes in XML file, and demonstrates the use of listener to check the checkbox state – checked or unchecked.
P.S This project is developed in Eclipse 3.7, and tested with Android 2.3.3.

1. Custom String

Open “res/values/strings.xml” file, add some user-defined string.
File : res/values/strings.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="hello">Hello World, MyAndroidAppActivity!</string>
    <string name="app_name">MyAndroidApp</string>
    <string name="chk_ios">IPhone</string>
    <string name="chk_android">Android</string>
    <string name="chk_windows">Windows Mobile</string>
    <string name="btn_display">Display</string>
</resources>

2. CheckBox

Open “res/layout/main.xml” file, add 3 “CheckBox” and a button, inside the LinearLayout.
File : res/layout/main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
 
    <CheckBox
        android:id="@+id/chkIos"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/chk_ios" />
 
    <CheckBox
        android:id="@+id/chkAndroid"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/chk_android"
        android:checked="true" />
 
    <CheckBox
        android:id="@+id/chkWindows"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/chk_windows" />
 
    <Button
        android:id="@+id/btnDisplay"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/btn_display" />
 
</LinearLayout>
Make CheckBox is checked by default
Put android:checked="true" inside checkbox element to make it checked bu default. In this case, “Android” option is checked by default.

3. Code Code

Attach listeners inside your activity “onCreate()” method, to monitor following events :
  1. If checkbox id : “chkIos” is checked, display a floating box with message “Bro, try Android”.
  2. If button is is clicked, display a floating box and display the checkbox states.
File : MyAndroidAppActivity.java
package com.mkyong.android;
 
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.Toast;
 
public class MyAndroidAppActivity extends Activity {
 
  private CheckBox chkIos, chkAndroid, chkWindows;
  private Button btnDisplay;
 
  @Override
  public void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.main);
 
	addListenerOnChkIos();
	addListenerOnButton();
  }
 
  public void addListenerOnChkIos() {
 
	chkIos = (CheckBox) findViewById(R.id.chkIos);
 
	chkIos.setOnClickListener(new OnClickListener() {
 
	  @Override
	  public void onClick(View v) {
                //is chkIos checked?
		if (((CheckBox) v).isChecked()) {
			Toast.makeText(MyAndroidAppActivity.this,
		 	   "Bro, try Android :)", Toast.LENGTH_LONG).show();
		}
 
	  }
	});
 
  }
 
  public void addListenerOnButton() {
 
	chkIos = (CheckBox) findViewById(R.id.chkIos);
	chkAndroid = (CheckBox) findViewById(R.id.chkAndroid);
	chkWindows = (CheckBox) findViewById(R.id.chkWindows);
	btnDisplay = (Button) findViewById(R.id.btnDisplay);
 
	btnDisplay.setOnClickListener(new OnClickListener() {
 
          //Run when button is clicked
	  @Override
	  public void onClick(View v) {
 
		StringBuffer result = new StringBuffer();
		result.append("IPhone check : ").append(chkIos.isChecked());
		result.append("\nAndroid check : ").append(chkAndroid.isChecked());
		result.append("\nWindows Mobile check :").append(chkWindows.isChecked());
 
		Toast.makeText(MyAndroidAppActivity.this, result.toString(),
				Toast.LENGTH_LONG).show();
 
	  }
	});
 
  }
}

4. Demo

Run the application.
1. Result :
android checkbox demo 1
2. If “IPhone” is checked :
android checkbox demo2
3. Checked “IPhone” and “Windows Mobile”, later, click on the “display” button :
android checkbox demo3

Download Source Code

Download it – Android-Checkbox-Example.zip (15 KB)

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